textbox with auto buttons

Hi,

I am wanting to add the facitlity of adding the html bold, italics, and underline tags to a textbox around some selected text. For example, I have a page where people can submit a form via a post method. They can type there message into this box but I want to have 3 buttons (bold, italics and underline). When the person selects the text they want bolded it will put the html tags (<B></b> ) around the highlighted text. Does anyone know how this can be done? I don't have a lot of knowledge with javascript so an example would be great. Thanks in advance.

Dave